> Right, but you can't do this without punching holes in your firewall, and I assert that's not a desirable tradeoff, at least for consumer use cases. As far as

> Right, but you can't do this without punching holes in your firewall, and I assert that's not a desirable tradeoff, at least for consumer use cases. As far as I can tell, you still need an arbiter with a public IP address. That's true, but setting up these firewall rules dynamically is way easier than setting up NAT mappings (for example, UPnP through two different NATs never works properly). And even for consumer use cases, gateways could provide a way to allow all traffic to a specific destination, as most operating systems should provide a proper firewall. Of course, there is still work to be done, the UI for these firewalls should be made better (for example, allowing an application to request to accept incoming packets, and letting the user choose if it should only for the LAN, or for the whole Internet, etc). Indeed IPv6 by itself will not make p2p stuff painless, but it's still a better basis than IPv4.